1.Field of the Invention
The invention relates to an in-line height measurement system for planar fuel cell, especially a height measurement system that has simple operation and immediate access to measurement data.
2.Description of the Prior Art
Planar solid oxide fuel cell (SOFC) is a fuel cell that is used in high temperature environment. The sealing method for its cell stack includes compressive seal and ceramic glass seal. The compressive seal is a common method for low temperature sealing with the main advantages in easy disassembly and simple sealing principle. However, the biggest problem with this method is little availability for gasket material and high requirement for assembly precision. Ceramic glass seal is presently a more common sealing method for cell stack because it offers flexibility and elasticity at high temperature and suitability for SOFC operation at high temperature. It is also because the glass seal material thickness can be changed with pressure at high temperature. This will help reduce the difficulty in cell stack assembly design. The ability for thickness variation can compensate for the errors from design or fabrication. So the thickness variation with time and temperature is a critical parameter to design or operation. It is necessary to have an appropriate measurement and investigation on this parameter. Besides, there are other subjects that require cell stack height measurement to understand cell stack performance. Therefore, the measurement on cell stack height is imperative.
Traditional cell stack height measurement method for planar solid oxide fuel cell (SOFC) mainly includes the following steps: 1.After cell stack is assembled, using caliper to measure the heights at four corners and record them; 2.After cell stack is through high temperature sintering and the first time performance test, lowering the temperature, opening the furnace and re-measuring the heights at the four corners; 3.Subtracting the height of the second measurement from the height of the first measurement to obtain height change for the four corners; 4.taking the average for the height at the four corners to obtain the average height change.
The above procedure is time-consuming and poses difficulty in operation in addition to failing to correlate time or temperature to height change. It is difficult to control the temperature and time for glass seal material and immediately obtain height change data.
Therefore, the procedure does not satisfy the needs in an actual application
In view of the shortcomings with the traditional cell stack height measurement, the inventor has found improvement in this invention.